Tempo-Free Concepts Part One: Offensive And Defensive Efficiency

The NC State basketball team plays its first exhibition game tonight in Reynolds Coliseum against Div-II St. Paul's College, and with the regular season opener just a week away, I think it's a good time for a tempo-free stats refresher.  Long time readers know the deal by this point, so this is primarily for new readers who would otherwise be lost in the alterna-stat reality in which this blog lives during basketball season. 

Offensive and Defensive Efficiency

Rather than compare teams' per-game outputs, I prefer instead to look at how many points they score or allow per possession.

Why?  The difference between the fastest team in college basketball last season (VMI) and the slowest (Iowa) was nearly 25 possessions per 40 minutes.  VMI's run-and-gun style afforded it more than 81 possessions a night, while Iowa plodded its way to a Princeton-esque 57.  Just within the ACC, the difference between the fastest (UNC) and the slowest (that's us) was 10 possessions per 40 minutes. Those are significant opportunity gaps, so we've got to take tempo out of the equation in order to correct for those gaps and put the teams on equal footing.  Looking at per possession output does just that. 

Offensive efficiency = points scored / possessions x 100
Defensive efficiency = points allowed / possessions x 100

It's simple yet considerably more insightful than PPG, and that's the beauty of it.  The multiplier is there to make the numbers easier on the eyes.  In any given game, obviously, one team is going to score more points than the other; to put that in tempo-free terms, the winning team is the more efficient team.

These numbers tell us whether an offense or defense is good or bad.  Next up: understanding why they're good or bad -- the four factors.

Further reading.

As always, I welcome your questions.